1. Field of the Invention
The present invention relates to a planetary gear type speed change device for an automatic transmission for a vehicle such as an automobile.
2Description of the Prior Art
Various constructions have been proposed for a planetary gear type speed change device for an automatic transmission for a vehicle such as an automobile. These generally comprise one or more planetary gear mechanisms, and clutches and brakes for selectively interconnecting structural members such as sun gears, ring gears and carriers of the planetary gear mechanisms with one another or braking these with respect to the housing of the speed change device. Some of the clutches or the brakes are constructed as one-way clutches or one-way brakes to obtain automatic engagement or disengagement function of the clutches or the brakes during switching over of the speed stages provided by the speed change device.
Conventionally, the one-way clutches or the one-way brakes are generally used in such a manner that a certain clutch or brake selectively connects certain two relatively rotatable members with one another. In this manner of use the function of a one-way clutch or one-way brake is so limited.